This blog post will focus on the bash programming part of implementing a promise type. To understand what custom promise types are, and how to use them, you should read the introduction first.
To implement a custom promise type in CFEngine, you need a promise module. The module is an executable, and can be written in any language. It’s possible to write one from scratch, but to make it as easy as possible, we decided to provide libraries for common programming languages. In our previous blog post, we showed how to implement modules in Python. That’s great, it’s a powerful, expressive and readable programming language, however there is one drawback; installing python. Many systems don’t have python already, or have a version which is too old. So you will need to add policy to install / update Python, to make sure modules work correctly everywhere.
CFEngine 3.17.0 introduced custom promise types, which enable CFEngine users to extend core functionality and policy language in a simple way. As an example of the power and simplicity of this new feature, I will show a promise type that helps to observe a website’s status. The module which implements this promise type was written in a couple of hours.
Creating a promise type for whether a site is up We will use Python and the CFEngine library to implement a promise module. Our previous blog post, “How to implement CFEngine custom promise types in Python”, explains this in detail.
Several months ago I started the practice of using CFEngine Enterprise and its Mission Portal UI on a daily basis to manage the connected devices in my home. To start, I brought up an old desktop machine, cfengine-hub, to use as my hub and downloaded Enterprise, which is free for use up to 25 hosts. The next step in using best practices is to deploy policy from a version control repository. I use a local git server named git-server-zero instead of GitHub or GitLab as I like to be independent of the cloud when possible due to privacy and environmental concerns. I will use the Mission Portal Version Control Repository settings section to setup this repo as the source of policy for cfengine-hub.
Scalability is an important feature of any infrastructure management solution. Either the to-be-managed infrastructure is big already or it is expected to grow as the business grows. Over time more and more resources are needed for CI/CD pipelines and more customers use the product(s). Generally, growing a business means more traffic and requests need to be handled by the infrastructure. Hence, scalability is an important metric for comparing infrastructure management tools when deciding which one to use. Or which ones. Read our latest white paper, benchmarking and comparing the scalability of Ansible and CFEngine for large scale infrastructure management:
2020 is nearly over, and we’d like to take a couple of minutes to reflect on our year as well as provide a sneak peek into what you can expect from us in 2021. Although it has been a year full of distractions, the CFEngine team has continued to make significant strides when it comes to product improvements and new features that help our users.
Build powerful compliance reports based on important inventory data Compliance reports are high level reports, allowing you to see how compliant your infrastructure is. Checks are run against reporting data from all of your hosts, or a filtered subset, to find how many of them meet a certain compliance requirement. They are easy to build and use, entirely from the UI, with no programming needed, but flexible and powerful, allowing you to use package version information, custom inventory from your policy or even SQL queries if you need it. Compliance reports are not limited to a one regulation or framework, like CIS or HIPAA, but allow you to build your own checklists, based on your organizations requirements and compliance goals. See Compliance Reports in this video:
This tutorial focuses on how to write a promise module, implementing a new CFEngine promise type. It assumes you already know how to install promise modules and use custom promise types, as shown in the previous blog post.
Why Python? Promise modules can be written in any programming language, but there are some advantages of using python:
Readable and beginner friendly language / syntax Popular and familiar to a lot of people, also used in some CFEngine package modules Big standard library, allowing you to reuse data structures, parsers, etc. without reinventing the wheel or adding dependencies Official CFEngine promise module library Most of the code needed is already done (protocol, parsing, etc.) You can focus on only the business logic, what is unique to your new promise type With that said, there are some reasons why you might not always want to use python:
In CFEngine 3.17, custom promise types were introduced. This allows you to extend policy language, managing resources which don’t have built in promise types. The implementation of custom promise types is open source, and available in both CFEngine Enterprise and CFEngine Community. To implement a new custom promise type, you need a promise module. (The promise type is what you use in policy language (the concept), while the module is the underlying implementation - can be a python script, compiled executable or similar).
We are pleased to announce the release of CFEngine 3.17.0, with the theme Flexibility! This is a non-LTS release and allows the CFEngine community to test the features which will be in CFEngine 3.18.0 LTS (Summer 2021).
What’s new? A new look - Mission Portal Dark Mode Mission portal now gives you the option of switching to an alternate color theme, dark mode:
Trigger report collection from Host Info Page You no longer have to wait for the next reporting interval, or use the command line to get updated reports. Click the button on the host info page to trigger a report collection:
We are pleased to announce two new patch releases for CFEngine, version 3.12.6 and 3.15.3! These releases mainly contain bug fixes and dependency updates, but in 3.15.3 there are also some new enhancements in Mission Portal. The new cf-secret binary is also included in 3.15.3 packages.
New in Mission Portal 3.15.3 Synchronizing roles between Mission Portal and Active Directory When using LDAP for authentication, Mission Portal can now automatically grant roles based on the tags received from your LDAP server (for example Active Directory). This means that new users can start using Mission Portal immediately, without having to wait for an administrator to grant the appropriate roles manually. Enable this in Mission Portal Authentication Settings:
Ansible and CFEngine are two configuration management tools and at first glance they look like competitors - two tools dealing with the same problem, in very different ways. But are they? Maybe they are actually not dealing with the same problem and are not as incompatible as it seems. Read our Ansible|CFEngine white paper providing an analysis of this area to learn more:
